Hydrokinetic fluid drive



Aug-.29, 1967 1 R RITZEMA' 3,338,115 A` HYDBOKINETIC FLUID DRIVE FiledMay 18, 1964 I N VEN TOR.

new? @fifa/WQ wm ATTORNEY United States Patent O 3,338,115 HYDROKINETICFLUID DRIVE James R. Ritzema, Birmingham, Mich., assignor to GeneralMotors Corporation, Detroit, Mich., a corporation of Delaware Filed May18, 1964, Ser. No. 368,146 19 Claims. (Cl. 74--730) This inventionrelates to hydrokinetic uid drives and more particularly to hydrokineticuid couplings and torque converters.

The most common types of hydrokinetic ilud couplings and torqueconverters operate by causing the working iluid to travel underclosed-cycle conditions around the path of a closed annular vortex thusrequiring the iluid to make a continuous tight bend for each completefluid cycle around the vortex. As a result of this continuous sharpturning and dependent on the uid velocity, there occurs uid separationresulting in energy loss of varying magnitudes which reduces theefliciency of energy conversion. In the less common types ofhydrokinetic uid couplings and torque converters which operate bycausing the working fluid to travel under closed-cycle conditions arounda tortuous annular path, the eciency of energy conversion is furtherreduced below the etliciency level for nontortuous annular ilow sincethe iluid must turn for each curvature in the winding fluid path.

The hydrokinetic uid drive of this invention reduces the separation lossto increase energy conversion by providing a smoother path for uid flowand in addition is adaptable for single and divided input which includesa controlled input for hydrokinetic braking and single and dividedoutput which includes separate outputs for iiuid drive use as adifferential in place of the conventional geared diierential in thedrive train.

The hydrokinetic uid drive of this invention operates by causing theworking uid to travel under closed-cycle conditions around the path of apair of interconnected annular vorteXes as traced by a nonintersectingdouble looped or iigure eight curve. The iiuid drive structure comprisesa rotatable central dual path member providing separate crossoverpassages and a rotatable outer member on each side of the central dualpath member providing curved passages in the loop portions operativelyconnecting the terminal ends of the separate crossover passages toprovide a closed figure eight fluid coupling circuit. The pair of outermembers can serve as the input means for the uid drive to impart kineticenergy to the iiuid and in this instance serves as two separate pumpmeans with the central dual path member serving as the turbine means toprovide the output of the iluid drive. The central dual path member canalso serve as the i11- put means to impart kinetic energy to the uid andin that instance acts as the pump means with the pair of outer membersserving as the turbine means to provide a single iiuid drive output ortwo separate outputs. Where torque multiplication is desired, statormeans are placed in each loop to redirect the iluid ilow between theturbine means and pump means to provide closed figure eight torqueconverter circuitry.

When the pair of outer members serve as a separate pump means, powerinput from a prime mover may be equally divided between the separatepump means and if hydrodynamic braking is desired one of the pump meanscan be disconnected from the prime mover and held stationary formoderate braking or the prime mover can drive one of the pump means inreverse for greater braking.

When the central dual path member serves as the pump means, the outermembers which then serve as the turbine means can be connected toprovide a single output and Patented Aug. 29, 1967 can also be connectedindividually through suitable separate drive means to provide separateoutputs for diiferential iluid drive.

It is an object of this invention to provide a hydrokinetic liuid drivehaving a new and improved fluid ilow path.

It is another object of this invention to provide a new and improvedhydrokinetic iluid drive adapted for single and divided input includinga controlled input for hydrokinetic braking and single and dividedoutput including separate outputs for differential iluid drive.

It is another object of this invention to provide a hydrokinetic iiuiddrive which operates by causing the working uid to travel underclosed-cycle conditions around the path of a pair of interconnectedannular vortexes.

It is another object of this invention to provide a hydrokinetic tluiddrive having a iiow path including a pair of pump iiow paths and a pairof turbine flow paths with one pair having curved portions and thelother pair combining substantially straight portions and curvedportions and the curved portions having a radius of curvature at leasthalf the minimum torus diameter.

It is another object of this invention to provide a hydrokinetic uiddrive having a ow path including a pair of pump flow paths and a pair ofturbine flow paths with one pair of substantially constant curvature andthe other pair being arranged to cross over each other and havingsubstantially straight portions and .portions having an initial radiusof curvature at least half the minimum diameter of the torus.

It is another object of this invention to provide a hydrokinetic iluiddrive having a rotatable central dual path member serving as pumpingmeans and providing sep- -arate crossover passages, and a rotatableouter member serving as pump means on each side of the central dual pathmember providing curved passages operatively connecting the terminalends of the separate crossover passages to provide closed figure eightfluid coupling circuitry.

It is another object of this invention to provide a hydrokinetic uiddrive having a rotatable central dual path member serving as turbinemeans and providing separate crossover passages, and a rotatable outermember serving as pump means on each side of the central dual pathmember providing curved passages operatively connecting the terminalends of the separate crossover passages to provide closed liigure eightfluid coupling circuitry.

It is another object of this invention to provide a hydrokinetic fluiddrive having a rotatable central dual member serving as pump means andproviding separate crossover passages, a rotatable outer member on eachside of the central dual path member serving as turbine means andproviding curved passages, stator means providing passages to redirectflow between the turbine means and the pump means and the pump passages,turbine passages and stator passages being arranged to provide closednonintersecting double looped torque converter circuitry.

It is another object of this inventlon to provide a hydrokinetic uiddrive comprising a rotatable central dual path member serving as turbinemeans and providing separate crossover passages, a rotatable outermember on each side of the central dual path member serving as pumpmeans and providing curved passages, stator means to redirect ow betweenthe turbine means and pump means, and the pump passages, turbinepassages and stator passages being arranged to provide closednonintersecting double looped torque converter circuitry.

Itis another object of this invention to provide a hydrokinetic uiddrive which operates by causing the Working iuid to travel underclosed-cycle conditions around the path of a nonintersecting doublelooped curve and includes separate pump means one of which can be drivenin the same direction and speed as the other pump means and can also bedriven in a reverse direction and held stationary to providehydrokinetic braking.

It is another object of this invention to provide a hydrokinetic uiddrive which operates yby causing the working fluid to travel underclosed-cycle conditions around the path of a nonintersecting doublelooped curve and includes separate turbine means which can provide acombined single output and can also provide separate outputs fordifferential fluid drive.

These and other objects of the invention will be more apparent from thefollowing description of the preferred embodiments of the inventionillustrated in the accompanying drawing in which:

FIGURE 1 is a diagrammatic showing of the upper one half of oneembodiment of a hydrokinetic fluid drive unit possessing features ofthis invention.

FIGURE 2 is a representative View taken on the line 2-2 in FIGURE 1.

FIGURE 3 is a diagrammatic showing of the upper one half of anotherembodiment of a hydrokinetic fluid drive unit possessing `features ofthis invention.

FIGURE 4 is a modification of the hydrokinetic uid drive unit shown inFIGURE 1.

FIGURE 5 is a modification of the hydrokinetic fluid drive unit shown inFIGURE 3.

Referring first to FIGURE 1, the hydrokinetic fluid drive unit generallydesignated at basically comprises a pair of rotatable vaned pumps 12 and14, :a rotatable twin turbine 16 centrally located between pumps 12 and14, a vaned stator 18 between one exit side of turbine 16'and theentrance side of pump 12 and another vaned stator 20 located betweenanother exit side of turbine 16 and the entr-ance side of pump 14, allmounted in a transmission housing 22.

Input to drive pumps 12 and 14 in a forward direction is from a suitableprime mover, not shown, via a mechanical drive which includes a primemover driven shaft 24 driving a gear 26 in mesh with an externallytoothed annular gear 28 rigidly connected to a pumpvhousing 30. Pumphousing 30 in addition to rigidly connecting pumps 12 :and 14 to gear 28generally also provides the rotating fluid drive housing enclosing thefluid drive blading.

The stators 18 and 20 are prevented from reverse rotation by one-waybrakes 32 and 34 respectively which are grounded to the transmissionhousing 22 and which are operable to permit overnmning of stators 18 and20 in the forward direction in the known manner. Stators 18 and 20,which may also be controlled by suitable pitch control means, act as thereactionary members in the uid drive to collect the flow from turbine116 and redirect the ow to pumps 12 and 14 respectively with drive inthe forward direction being taken from turbine 16 via an output shaft36.

The working fluid as shown by the directional arrows travels underclosed-cycle conditions around the path of a pair of interconnectedannular vortexes as traced by a nonintersecting double looped or figureeight curve the two vortexes or loop centers being located equidistantfrom the common central axis of the pumps 12, 14, twin turbine 16 andstators 18, 20. This fluid path is provided by the arrangement of thefluid drive members in which the twin turbine 16 is a central dual pathmember having circumferentially spaced and separated turbine passages 38and 40 which cross over each other at their midpoints as shown inFIGURES 1 and 2. Turbine passages 38 are arranged to receive the uidfrom the exit side of pump 12 and deliver the uid to the entrance sideof stator 20 for subsequent delivery to the entrance side of pump 14.The turbine passages 40 are arranged to receive the fluid from the exitside of pump 14 and deliver the fluid to the entrance side of stator 18for subsequent delivery to the entrance side of pump 12.

In the region where turbine passages 38 and 40v cross each other, theheights of these passages both upstream and downstream of the crossoverpoints gradually increase reaching a maximum at the crossover points tocompensate for their gradual decrease in widths which permits the crossover so that theirareas are either substantially equal to their areasimmediately upstream and downstream of the crossover region or graduallydecrease in the direction of uid flow. This discourages fluid separationwhich might otherwise be promoted `if a diverging ow condition werepermitted to occur immediately downstream of the crossover region. Theareas of turbine passages 38 and 40 gradually become smaller Vtowardstheir exit ends to provide both a converging ilow condition for insuringagainst ow separation and a high flow velocity at the entrances to thepumps 12 and 14 as will be explained in greater detail later.

The vanes of the pumps 12, 14 and stators 18, 20 and the turbinepassages '38 and 40 are designed to provide entrance and exit angleswhich offer the least flow resistance with pumps 12 and 14 providing thegreatest curvature for bending the flow in the looped portions of theflow path and the turbine passages 38 and 40 and vaned stators 18 and 20providing a gradual curvature so that separation losses may be reducedand greater efficiency of energy conversion can be gained.

Describing now the operation, when the prime mover is started shaft 24immediately begins to rotate pump 4housing 30 in lthe forward directionwith power input being equally divided between pumps 12 and 14. As pumps12 and 14 rotate, they impart a `centrifugal force to the -uid whichthrows the fluid out their exit sides and into the passages 38 and 40.The fluid flowing through turbine passages 38 then flows through stator20 to enter the entrance side of pump 14 and fluid owing through turbinepassages 40 ows through stator 18 to enter the entrance side of pump 12.Since the load, not shown, to which turbine output shaft 36 is drivinglyconnected is originally at a standstill, turbine 16 is also stationary.With the prime mover idling, the uid emerging Ifrom pumps 12 and 14 hascomparatively little speed and circulates around the pair of annularvortexes provided by this ow path without imparting motion to turbine16. To accelerate the load, the prime mover is accelerated to rapidlyincrease the speed of pumps 12 and 14 up to a point where a relativelyhigh torque is produced by the pn'me mover, the maximum prime moverspeed that can be obtained while turbine 16 remains stationary beingknown as the stall point which occurs within the range of prime moverspeed at which maximum torque is produced.

The high torque output of the prime mover is reflected in fluid driveunit 10 in the form of greatly increased speed of the pumps 12 and 14which then hurl a considerable ramount of fluid from their exit sidesinto the entrances to turbine passages 38 and 40 respectively. Theturbine passages 38 and 40 are shaped to effect a maximum redirection ofthe uid streams so that a direct force is brought to bear on turbine 16with the direction of the fluid which leaves turbine passages 38 and 40being opposite to that of the forward rotation ofthe pumps 12 and 14.

While the turbine 116 remains stationary, it cannot extract wor-k fromthe fluid that is being directed by its passages. If no turbine work isextracted, the uid loses none of its energy in the process of fluidreversal except for small friction losses. However, when the fluidleaves turbine passages 38 vand 40 the uid stream has a greater velocitythan when it was discharged from pumps 12 and 14 since turbine passages38 and 40 gradually become smaller near their exits. The stators 18 and20 are designed to receive the fluid stream as it emerges from theturbine passages 40 :and 38 respectively land to turn it once more inthe direction of forward rotation of the pumps 12 and 14, the stators 18and 20 being held stationary against the force of the mpinging fluidstreams by the locking action of the one-way brakes 32 and 34respectively.

Like turbine 16 which still is presumed to be stationary, stators 18 and20 can extract no work and very little energy from the streams of fluid.But since there must be an equal and opposite reaction for every action,stators 18 and 20 exert a great resultant force upon the uid streamreturning it to the direction of pump rotation with little loss invelocity. Because the uid is moving in the same direction, the highvelocity uid stream leaving stators 18 and 20 enters pumps 12 and 14smoothly. Its velocity is then added to that developed in pumps 12 and14 so that the total velocity at the exits of the pumps 12 and 14 iscorrespondingly greater. This regenerative action is the key to thetorque multiplication process in the hydrokinetic torque converter.

Since the torque applied to turbine 16 increases with the amount ofiluid projected into it, the greater the pumps output velocities thegreater will be the torque on the turbine. The prime mover torqueapplied to pumps 12 and 14 is capable of laccelerating fluid in thefluid drive unit from rest to a certain velocity. Tlhen, if uid alreadyowing in the same direction with considerable velocity is supplied tothe pumps entrances, the pumps output velocities become the sum of thevelocity due to prime mover torque and the regenerative, or additional,input velocity.

Up to now it has been expedient to assume that turbine 16 remainstationary when the prime mover torque is applied through pumps 12 and14. This, however, is not the case since turbine 16 is connected to theload and is held stationary only until the torque applied to it issufiicient to overcome the inertia of the load. Since rapid accelerationis desired, the prime mover is caused to continuously accelerate. Bothpumps 12 and 14 and turbine 16 begin to pick up speed, but pumps 12 and14 are still rotating much faster than the turbine 16. The uid continuesto travel about the double looped ow path -at a considerable velocityproducing continuous torque multiplication. However, as the load to beaccelerated does accelerate the need for torque multiplicationdiminishes.

It will be observed that the iluid ow thus far described has all beenaround the double looped ow path of the uid drive unit. This circulationfrom pumps 12 and 14 to turbine 16 to the stators 18 and 20 and back tothe pumps 12 and 14 can be described as an open annular vortex type ofow as contrasted to the common closed annular vortex type of flow andvaries from a maximum at the stall -point to a minimum at the cruisingspeed. As turbine 16 begins to rotate, it can be seen that the uid inthe uid drive unit will also be carried around the periphery of thefluid drive unit resulting in what is called rotary ow. This rotarymotion of the uid becomes greater and the open vortex ow diminishes asthe speed of turbine 16 approaches that of pumps 12 and 14. How.- ever,both the open vortex and rotary ow are always present in the uid driveunit when the prime mover is driving the load because turbine speednever quite obtains pump speed. It is the open vortex flow whichprovides both the torque multiplication and fluid coupling within theuid drive unit.

As the load accelerates, the turbine speed increases causing the openannular vortex type of ow in the fluid drive unit to lessen and rotaryow to become greater. The more rapid rotation of turbine 16 createscentrifugal forces like those in the pumps 12 and 14. As these forcesincrease with speed in tur-bine passages 38 and 40, they resist the uidflow being projected into these passages from pumps 12 and 14. Thefaster moving turbine now runs away from the stationary stators 18 and20 reducing the effective velocity of the fluid discharged against thestators thus reducing the velocity of the uid stream when it isredirected into pumps 12 and 14 Iby the stators 18 and 20. Furthermore,the increase in prime mover speed as the load accelerates similarlycauses pumps 12 Vand 14 to -run away from stators 18 and 20 morerapidly. This further reduces the effectiveness of the fluid inputvelocity from the stators even though the basic pump output ow rates areincreased with faster pump rotation.

The overall effect of these changes is to reduce the open vortex fluidflow and regenerative effect from stators 18 and 20. Velocity of thefluid stream entering pumps 12 and 14 is gradually decreased, reducing,in turn both the fluid velocity at the pumps exits and the force on theturbine 16, and this process continues until all torque multiplicationceases and only prime mover torque is delivered to the turbine 16.

As the rotational speed of turbine 16 increases and approaches the speedof pumps 12 and 14, the direction of the fluid flow from the exits ofthe turbine passages 38 and 40 changes so that the uid ow exerts a forceon the backs of the vanes of the stators 18 and 20. Since this conditionwould cause turbulence resulting in increased friction and power loss,the one-way brakes 32 and 34 which brake only in a direction opposite tothat of pump and turbine rotation, permit stators 18 and 20 to freewheel.and be carried along with the rotating uid mass.

The hydrokinetic iluid drive unit 50 shown in FIGURE 3 comprises a pairof rotatable vaned turbines 52 and 54, a rotatable twin pump 56 locatedbetween turbines 52 and 54, a vaned stator 58 between the exit of theturbine 52 and one entrance side of pump 56 and another vaned stator 60between the exit of the turbine 54 and another entrance side of pump 56,all located within a transmission housing 62.

Input to drive pump 56 in the forward direction is by an input shaft 64which is rigidly connected to the pump housing which also generallyprovides the fluid drive housing for the iluid drive -blading One-waybrakes 82 and 84 for the stators 58 and 60 are grounded through a web 85of the transmission housing 62. Output 'from the turbines 52 and 54 isby a common output shaft 86 with the turbine 52 being directly connectedthereto and the vaned turbine 54 being connected thereto via a geartrain drive which provides a 1:1 drive ratio. The gear train drivecomprises an external toothed annular input gear 87 rigidly connected tothe turbine 54 in mesh with a first transfer gear 88 which is rigidlyconnected to a countershaft 89 rotatably supported in the web 85. rI'hecountershaft 89 is rigidly connected to a second transfer gear 92 whichis in mesh with an output gear 94 rigidly connected to the output shaft86. To provide the 1:1 drive ratio, Igears 88 and 92 are of the samesize and the gears 87 and 94 are of the same size.

The pump 56 which is the central dual path member has crossover passages98 and 100 like the crossover passages 38 rand 40 shown in FIGURE l andunlike the functioning of the passages 38 and 40 in FIGURE 1 aresuitably designed to serve as pump passages rather than turbinepassages. The direction of fluid ow about the double looped pathprovided by the arrangement of these uid dri-ve members is indicated bythe directional arrows. Upon rotation of pump 56 in the Kforwarddirection, the centrifugal force imparted to the fluid in pump passages98 forces this uid to flow radially outwardly to -enter the turbine 52and likewise the centrifugal force imparted to the tluid in pumppassages 100 forces this ui-d to ow `radially outwardly to enter theturbine 54. Fluid is thence delivered through the turbine 52 to enterthe stator 58 which redirects the flow to enter the pump passages 100 inthe same direction as pump rotation and the turbine 54 delivers the uidto stator 60 which redirects the ow to enter the pump passages 98 in thesame direction as pump rotation. Again, like the fluid drive unit shownin FIGURE l, the fluid travels under closed-cycle conditions around thesmooth double looped ow path provided by the curved pump passages 98,100 and the vanes of turbines 52, 54 and stators 58, 60 resulting inhigh level energy conversion. Tlhe uid drive unit 50 functions toprovide its greatest torque multiplication at stall with this torquemultiplication gradually decreasing until coupling speed is obtainedwhereafter the stators 58 and 60 are permitted to freewheel in theforward -direction of rotation by the one-way brakes 82 and 84.

The uid drive unit 110 shown in FIGURE 4 is a modification of the iluiddrive unit shown in FIGURE l and provides Ifor' two different degrees ofIhydrodynamic braking. The uid drive unit 110 comprises rotatable vanedpumps 112 and 114, a twin turbine 116 located between pumps 112 and 114,and vaned stators 118 and 120, all housed within a transmission housing122. Input is via the input shaft 124 driving the gear 126 which is inmesh with a gear 128, the latter gear being rigidly connected to thepump housing 130 which also generally provides the fluid drive housingfor the iluid drive blading. Stators 118 and 120 are prevented fromreverse rotation by the oneway brake 132 and 134 respectively which aregrounded to the transmission housing 122 and output from the turbine 116which has the crossover turbine passages 138 and 140 is via the outputshaft 136.

In this instance, only the pump 112 is directly connected to the pumphousing 130 and a planetary gear drive generally designated at 141 isprovided which is operable to drivingly connect the pump 114 to the pumphousing 130 so that the pump 114 may be either driven in the samedirection and at the same speed as pump housing 130 and pump 112 or maybe driven in reverse. The planetary gear drive includes a ring gear 142rigidly connected to the pump housing 130 meshing with planetary pinions143 supported on a planet carrier 144 which may be either heldstationary by a reverse drive brake 146 or connected to the ring gear142 by engagement of a lockup clutch 147. Pinions 143 mesh with a sungear 148 which is rigidly connected to the pump 114. Another brake 149when engaged is effective to hold both the sun gear 148 and pump 114stationary.

When the lockup clutch 147 is engaged and the remaining friction devicesare disengaged, the planetary gear drive 141 is effectively locked upand the pump 114 conjointly rotates in the forward direction with pump112 and the uid drive unit 110 operates in the same manner as fluiddrive unit 10, flow being in the direction of the arrows.

For moderate hydrodynamic braking, the reverse drive brake 146 andlockup clutch 147 are disengaged and only the brake 149 is engaged tohold stationary the pump 114 which then yacts as a reaction member andno longer takes part in the process of imparting energy. Since turbine116 is rotating forwardly, the fluid thrown from turbine passages 138 tothe stationary stator 120 and thence redirected by stator 120 to the nowstationarily held pump 114 for return to the turbine passages 140 is inthe form of high velocity tiuid jets which are continually sheared asthey travel between the stationary stator 120 and pump 114 and therapidly moving turbine passages 138 and 140.

Since this shearing energy must come from the turbine 116, the outputshaft 136 is retarded by a retarding effect which theoreticallyincreases as the square of the relative speed difference between theturbine 116 and the pump 114 and stator 120, the speed difference inthis instance being turbine speed.

For greater hydrokinetic braking, the lockup clutch 147 and the brake149 are disengaged and the reverse drive brake 146 is engaged so thatthe planet carrier 144 then acts as the reaction member of planetarygear drive 141. Since the pump housing 130 and ring gear 142 arerotating in the forward direction, the pinions 143 rotate about theirown axes and drive the sun gear 148 and connected pump 114 in thereverse direction, which is opposite the direction of forward rotationof the turbine 116, and at an increased speed. Since the turbine 116 andpump 114 are rotating in opposite directions, the retarding effectresulting from shearing of the fluid as it travels between the pump 114and turbine 116 is increased since the relative speed diiference nowbecomes the sum total of their respective speeds. Inv addition, thereoccurs the retarding effect due to fluid shear as it travels between theforwardly rotating turbine 116 and stationary stator 120 and between thestator 120 and pump 114 which is rotating in reverse. Under theseconditions, the uid exiting from the turbine passages 138 is not onlyprevented from rotary motion in t-he forward direction but is also knownin the reverse direction by the pump 114 whereby the tluid exiting fromthe pump 114 will tend to drive the turbine 116 in reverse to furthercontribute to the braking effect.

Referring now to FIGURE 5, there is shown a hydrokinetic fluid driveunit 150 which is a modification of the hydrokinetic iiuid drive unit50fshown in FIGURE 3 for use as a differential iluid drive in a vehicle.The fluid drive unit 150 comprises rotatable vaned turbines 152 and 154,a rotatable twin pump 156 having crossover turbine passages 157 and 158located between turbines 152 and 154 and vaned stators 159 and 160.Input for the fluid drive unit is from an internal combustion pistonengine 161 whose longitudinal axis is transverse of the longitudinalaxis of the vehicle chassis, not shown. Engine 161 has a crankshaft 163rigidly connected to a gear 164 in mesh with an externally toothedannular gear 165 which is rigidly connected to the pump housing 170.

One-way brakes 172 and 174 prevent reverse rotation of the stators 159and 160 and permit overruuning of the stators in the forward direction,the operation of this fluid drive unit being basically the same as thatof the fluid drive unit 50 shown in FIGURE 3 with uidow being in thedirection of the arrows. In this instance, however, instead of theoutputs of the turbines 152 and 154 being combined to provide a commonoutput, the turbine 154 provides a separate input to a selectivelycontrolled variable ratio gear box 176 to drive one driven wheel 178 ofthe vehicle and the turbine 152 provides a separate input to anotherselectively controlled variable ratio gear box 179 identical to gear box176 to drive the other driven wheel 180 and the one-way brakes 172 and174 are grounded through the gear boxes 179 and 176 'respectively.

In the forward drive ranges and reverse, the gear boxes 176 and 179which serve to extend the range of usefulness of the uid drive arecontrolled to provide identical drive -ratios between the turbine 154and wheel 178 and between the turbine 152 and Wheel 180. Since turbines152 and 154 are not mechanically interconnected nor are theymechanically connected to the pump 156 but rather they are hydraulicallyconnected through the operation of fluid flow, the turbines 152 and 154may revolve relative to the pump 156 and may also revolve relative toeach other as the result of reaction torque from the wheels 178 and 180during turning of the vehicle to per-mit the hydrokinetic drive unit toserve as a differential fluid drive to the wheels.

While the above hydrokinetic fluid drive units are illustrated as beingof the torque converter type by the employment of the vaned stators toprovide redirection of the ow and torque multiplication, it will bereadily understood that these vaned stators may be removed withoutdeparting from the scope of this invention so that the hydrokineticfluid drive units can be used as fluid couplings where that type ofoperation is desired. Y

The above-described preferred embodiments are illustrative oftheinvention which may be modified within the scope of the appended claims.

I claim:

1. In `a hydrokinetic uid drive,

(a) a hydrokinetic fluid drive unit comprising rotary input means androtary output means cooperatively providing closed iluid circuit meanscontaining fluid,

(b) said input means comprising centrifugal pumping means operable whendriven to impart kinetic energy only by centrifugal action to the fluidcontained in said closed fluid circuit means, said output means beingresponsive to be driven by the kinetic energy imparted to the fluidcontained in said closed uid circuit means,

(c) and said closed fluid circuit means having a continuousnon-intersecting fluid path which crosses over itself.

2. In a hydrokinetic uid drive,

(a) a hydrokinetic tuid drive unit comprising input means and outputmeans which are rotatable only about a single common central axis andhave closed uid circuit means containing uid,

(b) said input means being operable when driven to impart kinetic energyto the lluid contained in said closed fluid circuit means, said outputmeans being responsive to be driven by the kinetic energy irnparted tothe tluid contained in said closed fluid circuit means,

(c) and said closed fluid circuit means having a continuous double loopliuid path which crosses over itself and whose loop centers are at thesame radius from said central axis.

3. In a hydrokinetic fluid drive,

(a) a hydrokinetic uid drive unit comprising a pair of pumps and aturbine providing closed uid circuit means containing liuid,

(b) said pumps being operable when driven to impart kinetic energy tothe liuid contained in said closed uid circuit means, said turbine beingresponsive to be driven by the kinetic energy imparted to the uidcontained in said closed uid circuit means,

(c) and said closed uid circuit means providing a uid path traced by anonintersecting ligure eight curve.

4. In a hydrokinetic uid drive,

(a) a hydrokinetic drive unit comprising a pump and a pair of turbinesproviding closed tluid circuit means containing uid,

(b) said pump being operable when driven to impart kinetic energy to theliuid contained in said closed uid circuit means, said turbines beingresponsive to be driven by the kinetic energy imparted to the uidcontained in said closed fluid circuit means,

(c) and said closed fluid circuit means providing a fluid path traced bya nonintersecting figure eight curve.

5. The hydrokinetic iiuid drive set forth in claim 4 and said turbinesbeing drivngly connected to each other to provide a combined singleoutput.

6. In a hydrokinetic uid drive,

(a) a hydrokinetic uid drive unit comprising input means and outputmeans providing closed iluid circuit means containing iiuid,

(b) said closed Huid circuit means providing a fluid path traced by anonintersecting double looped curve whereby said hydrokinetic uid driveunit operates t'o drive said output means by causing uid to iow aroundthe uid path traced by said nonintersecting double looped curve Whensaid input means is driven,

(c) said input means including a pair of pumps arranged so that one ofsaid pumps provides a portion of said closed uid circuit means in one ofthe loops of said double looped curve and the other of said pumpsprovides a portion of said closed fluid circuit means in the other loopof said 'double looped curve,

(d) and said output'means including a twin turbine which is arrangedbetween said pumps and provides separate crossover passages for saidclosed uid circuit means eiective to interconnect said looped portionsprovided by said pumps.

Y 10 l 7. The hydrokinetic duid drive set forth in claim 6 and saidfluid circuit means having reaction means including stator meansarranged between each said pump and said twin turbine. 8. In ahydrokinetic uid drive,

(a) a hydrokinetic fluid drive unit comprising input means and outputmeans which are rotatable about a common axis and have closed uidcircuit means containing fluid,

(b) said closed fluid circuit means providing a iuid path traced by anonintersecting double looped curve whereby said hydrokinetic fluiddrive unit operates to drive said output means -by causing fluid to owaround the Huid path traced by said nonintersecting double looped curvewhen said input means is driven,

(c) said output means including a pair of turbines arranged so that oneof said turbines provides a portion of said closed uid circuit means inone of the loops of said double looped curve and the other of saidturbines provides a portion of said closed fluid circuit means in theother loop of said double looped curve,

(d) and said input means including a twin pump which is arranged betweensaid turbines and provides separate crossover passages for said closedliuid circuit means effective to interconnect said looped portionsprovided by said turbines.

9. The hydrokinetic fluid drive set forth in claim 8 and said uidcircuit means having reaction means in- 30 cluding stator means arrangedbetween each said turbine and said twin pump.

10. In a hydrokinetic uid drive,

(a) a hydrokinetic fluid drive unit comprising input means and outputmeans which are rotatable about a common central axis and have closedfluid Circuit means containing lluid,

(b) said closed fluid circuit means providing a fluid path traced by anonintersecting double looped curve whose loop centers are equidistantfrom said central axis whereby said hydrokinetic uid drive unit operatesto drive said output means by causing uid to low around the uid pathtraced by said nonintersecting double looped curve when said input meansis driven, v

(c) said input means including a pair of pumps arranged so that one ofsaid pumps provides a portion of said closed fluid circuit means in oneof the-loops of said double looped curve and the other of said pumpsprovides a portion of said closed fluid circuit means in the other loopof said double looped curve,

(d) and said output means including a twin turbine which is arrangedbetween said pumps and provides separate crossover passages for saidclosed fluid circuit means effective to interconnect said loopedportions provided by said pumps.

11. In a hydrokinetic uid drive,

(a) a hydrokinetic fluid drive unit comprising input means and outputmeans which are rotatable about a common central axis and have closeduid circuit means containing liuid,

(b) said closed Huid circuit means providing a fluid path traced by anonintersecting double looped curve whose loop centers are equidistantfrom said central axis whereby said hydrokinetic luid drive unitoperates to drive said output means by causing fluid to flow around thefluid path traced by said nonintersecting double looped curve when saidinput means is driven,

(c) said input means including a twin pump which is arranged betweensaid turbines and provides separate crossover passages for said closedfluid circuit means eiective to interconnect said looped portionsprovided by said turbines,

(d) and said outputvmeans including a pair of turbines arranged so thatone of said turbines provides a portion of said closed uid circuit meansin one of the loops of said double looped curve and the other of saidVturbines provides a portion of said closed v iluid circuit means in theother loop of said double looped curve.

12, In a hydrokinetic fluid drive,

(a) a hydrokinetic uid drive unit comprising input means, reaction meansand output means providing closed iluid circuit means containing uid,

(b) saidclosed uid circuit means providing a fluid path traced by anonintersecting double looped curve whereby said hydrokinetic fluiddrive unit operates to drive said output means by causing uid to flowaround the uid path traced by said nonintersecting double looped curvewhen said input means is driven,

(c) said input means including a twin pump which is arranged betweensaid turbines and provides separate crossover passages for said closedfluid circuit means,

V(d) said output means including a pair of turbines arranged so that oneof said turbines provides a portion of said closed uid circuit means inone of the loops of said double looped curve and the other of saidturbines provides a portion of said closed fluid circuit means in theother loop of said double looped curve,

(e) said reaction means including stator means between each said turbineand said twin pump,

(f) ,andi selectively controlled yvariable ratio drive means operable todrivingly connect each said turbine topa separate load in a plurality ofdifferent drive ratios with said hydrokinetic uid drive unit beingeffective to serve as a differential uid drive t said loads. l

13. In a hydrokinetic uid drive,

(a) a hydrokinetic fluid drive unit comprising a pair of pumps and atwin turbine providing closed fluid circuit means containing uid,

v(b) said fluid circuit means providing a tluid path traced by anonintersecting double looped curve,

(c) said pair of pumps having passage means providing the outercurvature ofthe looped portions of said looped curve for said closed uidcircuit means and being elective when driven in one direction to impartkinetic energy to the fluid contained in said uid circuit means, saidtwin turbine being arranged between said pumps and having crossoverpassage means providing the nonintersecting portion of said looped curvefor said closed iuid circuit means effective to interconnect the passagemeans of said pumps, said twin turbine being responsive to the kineticenergy imparted to the uid contained in said uid circuit means to bedriven in said one direction,

(d) and drive means eiective to selectively connect and disconnect saidpumps, said drive means being operable to provide a direct drive betweensaid pumps whereby said pumps are conditioned for drive in the samedirection at the same speed and brake means operable when engaged tohold one of said pumps stationary when said one pump is disconnectedfrom the other of said pumps by said drive means to provide hydrodynamicbraking.

14. In a hydrokinetic uid drive,

(a) a hydrokinetic fluid drive unit comprising a pair of pumps, a twinturbine and a pair of stators providing closed uid circuit meanscontaining iluid and having a common central axis,

I (b) said fluid circuit means providing a uid path traced by anonintersecting double looped cur-ve whose loop centers are equidistantfrom said central axis, Y

(c) said pair of pumps having passage means providing theroutercurvature of the looped portions of said -looped curve for said closediluid circuit means and Y being effective when driven in one directionto impart kinetic energy to the iluid contained in said fluid circuitmeans, said twin turbine being arranged between said pumps and saidstators and having crossover passage means providingthe nonintersectingportion of said looped curve for said closed uid circuit means, saidtwin turbine being responsive to the kinetic energy imparted to thefluid contained in said uid circuit means to be driven in said onedirection,

(d) and drive means effective to selectively connect and disconnect saidpumps, said drive means in a irst selective condition being operable toprovide a direct drive between said pumps whereby said pumps areconditioned for drive in the same direction at the same speed for normaluid drive operation, in a second selective condition being operable toprovide a reverse drive between said pumps whereby said pumps areconditioned for drive in opposite directions to provide one degree ofhydrodynamic braking and brake means operable when engaged to hold oneof said pumps stationary when said one pump is disconnected from theother of said pumps by said drive means to provide a lesser degree ofhydrodynamic braking.

15. The hydrokinetic drive set forth in claim 14 and said drive meanscomprising a sun gear, a ring gear and a planet carrier having pinionsmeshing with said sun gear and said ring gear, said ring -gear beingdrivingly connected to said other pump, said sun -gear being drivinglyconnected to said one pump, a clutch operable when engaged to preventrelative rotation between said ring ygear and said planet carrierwhereby said irst selective condition is effected and a brake operablewhen engaged to hold said planet carrier whereby said second selectivecondition is eiected. v

16. In a hydrokinetic uid drive,

(a) a hydrokinetic iluid drive unit comprising rotary pump means androtary turbine means having a common axis of rotation and providingfluid circuit means which contains uid and provides a nonintersectingligure eight flow path,

(b) said flow path defined by a pair of rotary llow passages provided bysaid pump means and rotatable about said axis, and a pair of rotary flowpassages provided by said turbine means and rotatable about said axis,

(c) one of said pair of How passages having a substantially constantcurvature,

(d) and the other of said pair of ow passages having substantiallystraight portions and portions having a radius of curvature at leastequal to the minimum radius of curvature of said one pair of owpassages.

17. In a hydrokinetic uid drive,

(a) a hydrokinetic uid drive unit comprising rotary pump means androtary turbine means having a common axis of rotation and providingclosed fluid circuit means which contains fluid and provides acontinuous flow path,

(b) said continuous flow path dened by a pair of rotary flow passagesprovided by said pump means and rotatable about said axis, and a pair ofrotary ow passages provided b-y said turbine means and rotatable aboutsaid axis,

(c) one of said pair of flow passages having a substantially constantcurvature,

(d) and the other of said pair of ow passages being arranged to crossover each other and having substantially straight portions and portionshaving an initial radius of curvature at least equal to the minimumradius of curvature of said one pair of ow passages.

18. In a hydrokinetic uid drive,

(a) centrifugal pumpA passage means operable only by centrifugal actionto supply fluid energy,

(b) turbine iluid passage means operable to extract huid energy,

(c) and one of said rotary uid passage means having crossover passagemeans for cooperating with the other of said rotary uid passage means toprovide a closed uid circuit having a continuous nonintersecting doublelooped ow path to establish a uid drive connection between said inputand output uid passage means.

19. In a hydrokinetic fluid drive,

(a) a rotary input uid passage means operable to supply uid energy,

(b) rotary output uid passage means operable to extract uid energy,

(c) one of said rotary uid passage means having crossover passa-ge meansfor cooperating with the other of said rotary fluid passage means toprovide a closed fluid circuit having a continuous nonintersectingdouble looped ow path to establish a uid drive connection between saidinput and output fluid passage means, and

(d) said input and output uid passage means having a common central axisof rotation, said loops having their centers located at the same radiusfrom said axis.

References Cited UNITED STATES PATENTS DONLEY J.

20 DAVID I. WILLIAMOWSKY, J. R. BENEFIEL,

Examiners.

2. IN A HYDROKINETIC FLUID DRIVE, (A) A HYDROKINETIC FLUID DRIVE UNIT COMPRISING INPUT MEANS AND OUTPUT MEANS WHICH ARE ROTATABLE ONLY ABOUT A SINGLE COMMON CENTRAL AXIS AND HAVE CLOSED FLUID CIRCUIT MEANS CONTAINING FLUID, (B) SAID INPUT MEANS BEING OPERABLE WHEN DRIVEN TO IMPART KINETIC ENERGY TO THE FLUID CONTAINED IN SAID CLOSED FLUID CIRCUIT MEANS, SAID OUTPUT MEANS BEING RESPONSIVE TO BE DRIVEN BY THE KINETIC ENERGY IMPARTED TO THE FLUID CONTAINED IN SAID CLOSED FLUID CIRCUIT MEANS, (C) AND SAID CLOSED FLUID CIRCUIT MEANS HAVING A CONTINUOUS DOUBLE LOOP FLUID PATH WHICH CROSSES OVER ITSELF AND WHOSE LOOP CENTERS ARE AT THE SAME RADIUS FROM SAID CENTRAL AXIS.
 14. IN A HYDROKINETIC FLUID DRIVE, (A) A HYDROKINETIC FLUID DRIVE UNTIT COMPRISING A PAIR OF PUMPS, A TWIN TURBINE AND A PAIR OF STATORS PROVIDING CLOSED FLUID CIRCUIT MEANS CONTAINING FLUID AND HAVING A COMMON CENTRAL AXIS, (B) SAID FLUID CIRCUIT MEANS PROVIDING A FLUID PATH TRACED BY A NONINTERSECTING DOUBLE LOOPED CURVE WHOSE LOOP CENTERS ARE EQUIPDISTANT FROM SAID CENTERAL AXIS, (C) SAID PAIR OF PUMPS HAVING PASSAGE MEANS PROVIDING THE OUTER CURVATURE OF THE LOOPED PORTIONS OF SAID LOOPED CURVED FOR SAID CLOSED FLUID CIRCUIT MEANS AND BEING EFFECTIVE WHEN DRIVEN IN ONE DIRECTION IMPART KINETIC ENERGY TO THE FLUID CONTAINED IN SAID FLUID CIRCUIT MEANS, SAID TWIN TURBINE BEING ARRANGED BETWEEN SAID PUMPS AND SAID STATORS AND HAVING CROSSOVER PASSAGE MEANS PROVIDING THE NONINTERSECTING PORTION OF SAID LOOPED CURVE FOR SAID CLOSED FLUID CIRCUIT MEANS, SAID TWIN TURBINE BEING RESPONSIVE TO THE KINETIC ENERGY IMPARTED TO THE FLUID CONTAINED IN SAID FLUID CIRCUIT MEANS TO BE DRIVEN IN SAID ONE DIRECTION, (D) A DRIVE MEANS EFFECTIVE TO SELECTIVELY CONNECT AND DISCONNECT SAID PUMPS, SAID DRIVE MEANS IN A FIRST SELECTIVE CONDITION BEING OPERABLE TO PROVIDE A DIRECT DRIVE BETWEEN SAID PUMPS WHEREBY SAID PUMPS ARE CONDITIONED FOR DRIVE IN THE SAME DIRECTION AT THE SAME SPEED FOR NORMAL FLUID DRIVE OPERATION, IN A SECOND SELECTIVE CONDITION BEING OPERABLE TO PROVIDE A REVERSE DRIVE BETWEEN SAID PUMPS WHEREBY SAID PUMPS ARE CONDITIONED FOR DRIVE IN OPPOSITE DIRECTIONS TO PROVIDE ONE DEGREE OF BYDRODYNAMIC BRAKING AND BRAKE MEANS OPERABLE WHEN ENGAGED TO HOLD ONE OF SAID PUMPS STATIONARY WHEN SAID ONE PUMP IS DISCONNECTED FROM THE OTHER OF SAID PUMPS BY SAID DRIVE MEANS TO PROVIDE A LESSER DEGREE OF HYDRODYNAMIC BRAKING.
 15. THE BYDROKINETIC DRIVE SET FORTH IN CLAIM 14 AND SAID DRIVE MEANS COMPRISING A SUN GEAR, A RING GEAR AND A PLANET CARRIER HAVING PINIONS MESHING WITHSAID SUN GEAR AND SAID RING GEAR, SAID RING GEAR BEING DRIVINGLY CONNECTED TO SAID OTHER PUMP, SAID SUN GEAR BEING DRIVINGLY CONNECTED TO SAID ONE PUMP, A CLUTCH OPERBLE WHEN ENGAGED TO PREVENT RELATIVE ROTATION BETWEN SAID RING GEAR AND SAID PLANET CARRIER WHEREBY SAID FIRST SELECTIVE CONDITION IS EFFECTED AND A BRAKE OPERABLE WHEN ENGAGED TO HOLD SAID PLANET CARRIER WHEREBY SAID SECOND SELECTIVE CONDITION IS EFFECTED. 